The chemistry between conductors and their orchestras declares itself by result rather than action, and there are times when the action doesn't amount to much at all. Witness the long-term love-affair between the London Symphony and Rostropovich. From the visual evidence of Rostropovich flailing around on the rostrum, all elbows, air-hugs and decisive downbeats on a scarcity alert, you might expect the worst. But in fact, it almost always ends up with astounding music. Especially when the music is Russian and the Russian is Shostakovich, whose 15 symphonies have been the chief preoccupation of the LSO this year. The first half of a complete cycle ran through February and March at the Barbican. The second half has just begun. And I doubt if you'd find a more authentic rendition of these mostly dark, bitter and painful scores anywhere in the world at the moment. Even in Russia itself, where tradition runs deep, but is compromised by questionable standards and a wavering grasp of the distinction between sentience and sentiment.

With Rostropovich and the LSO you get a sort of flaying of the soul, a fierce pursuit of the truth that throws up lots of violent aural gore. And whatever the truth of the Shostakovich symphonies may be, you can be sure that these performances are digging deep for it. Which is more than can be said for the notes in the impressive-looking programme-book compiled for the cycle. As I mentioned on this page back in the Spring, the notes are one-dimensional: written as though Testimony (the posthumous memoir of Shostakovich which provoked a radical rereading of his work) had never been published. Testimony has, of course, been proved unreliable on matters of detail, but its broad picture - of a composer in fear of his life and liberty, hiding the personal meaning of his music behind a veneer of public statement - is generally considered accurate.

Tuesday's instalment of the cycle found Shostakovich very much in hiding - after the 1948 Zhdanov decree which attacked his work as "formalist" and "undemocratic", with "contempt for melody" and "neuropathic discords alien to the artistic taste of the Soviet people". After Zhdanov, Shostakovich had no place on Soviet concert platforms. He was reduced to writing for the cinema - blameless music, like the score for Michurin, which opened Tuesday's concert. All his other work was put on hold, including plans for a new symphony and violin concerto. Concertos were too obviously undemocratic to bear contemplation.

But in 1953, Stalin died; and with the immediate prospect of a softer political environment, the Violin Concerto No 1 and Symphony No 10 emerged in quick succession. They are twins stylistically, and share material, including the motto theme, D-Eflat-C-B (D-S-C-H in German nomenclature), which became Shostakovich's musical signature. And the endlessly repeated insistence of that theme delivers a clear message. I'm still here, says Shostakovich. Through the terror, I survived.

Perhaps it takes a Russian to appreciate quite what that means; and Rostropovich (in his early twenties at the time of Zhdanov) hammers out the notes like fist-blows on a prison door. It's an aural battery that's both magnificent and desperate. I've never heard a more exhilarating live performance of the 10th. Nor have I heard the Violin Concerto played with such hard-bitten force as here, by Maxim Vengerov. This is a tough piece - too tough for David Oistrakh, its original interpreter, who had the score modified to allow himself a rest between the cadenza and finale. Vengerov takes no rest, and he doesn't seem to need it. Tuesday's reading was all power-driven energy; a tour de force of staggering dimension.

s aside, few musical events this year have caught the public imagination so vividly as the emergence of Elgar's 3rd Symphony, realised from the composer's sketches by Anthony Payne. Since it premiered in February it has been played 10 times. There are 60 performances scheduled during the next year. And it has been the inspiration for a whole Elgar Festival, running over several weekends in Bristol as a joint collaboration between the university and the seriously up-and-coming Bristol-based Brunel Ensemble under its conductor, Christopher Austin. Last weekend was the pivotal event, with an Elgar study day and a performance of the 3rd Symphony itself. And the more I hear this piece, the more I find it the most striking repository of Elgar's late ideas about orchestral writing. The rawness of the opening bars, with their brazen, rising parallel fourths, is still slightly shocking. But it stays in the mind. And about that passage at least, there's no question of authenticity. Every note is Elgar's own.

Much of the rest, though, was left open-ended - especially the finale where Payne had to compose from scratch, fixing the course not only of that movement but of the entire piece. Technically, stylistically and temperamentally, his solutions are, I think, convincing. And though you might quibble with the soft gong-stroke at the very end - a touch Cecil B de Mille for Elgar - it works within the context that Payne creates, as an atmospheric winding-down on ghostly resonances of the opening theme.

In Bristol, the Brunel Ensemble did it proud, with a performance that wasn't tidy - the string entries could have done with some housekeeping - but was alive, driven on by technically assured conducting that made sense even if it sometimes pushed the pace. And it was good that the symphony came paired with a piece that showed what Anthony Payne sounds like when he's being himself: Time's Arrow, his 1990 Proms commission, which has never had a live public performance since its premiere at the Albert Hall. I can't think why. It's an explosively attractive score that asks a lot of its performers. But it rewards them too, in music that you might call "questioningly English". And again, it was a fine performance, rushed during the central section, but otherwise held together with nerves of steel and a technique to match by Christopher Austin. A class act that many a London orchestra would covet.

The joke in Donizetti's Daughter of the Regiment is about class - a rough girl from beneath the salt who suddenly finds herself above it - and English Touring Opera retells the joke very nicely in its new production, which opened at the Richmond Theatre on Wednesday. Sarah Rhodes, who played the girl in question, is a joy: robustly bottom-drawer, but with a voice that knows how to behave impeccably. Kit Hesketh-Harvey's singing translation is a hoot: none the worse, in this Offenbach-like opera comique, for its West End raciness. And though I'd expected a tighter feel for movement from the direction of Ian Spink (the Second Stride choreographer, branching out) it's an entirely upbeat show that makes one of the best ETO offerings in recent years. And there's another joke in this production, about Swiss identity and alpine scenes (the action happens in the Tyrol) which is so adroitly handled that the real star of the show is the designer, Yannis Thavoris, who delivers every opera company's dream of something stylish, sharp and clever on a tiny budget. Note the name. This is a major talent in the making.